Multiple ALS Mutations Confer Herbicide Resistance in Waterhemp (Amaranthus tuberculatus)

Weed Science ◽  
2007 ◽  
Vol 55 (5) ◽  
pp. 421-428 ◽  
Author(s):  
William L. Patzoldt ◽  
Patrick J. Tranel
Keyword(s):  
Leaf Disc ◽  
Acetolactate Synthase ◽  
Cross Resistance ◽  
Whole Plant ◽  
Amaranthus Tuberculatus ◽  
Susceptible Control ◽  
Als Inhibitors ◽  
Als Inhibitor ◽  
Disc Assay

In a survey of herbicide responses among Illinois waterhemp half-sib populations, several were observed with differential responses to imazethapyr and thifensulfuron, two acetolactate synthase (ALS)–inhibiting herbicides. Plants from two waterhemp populations were verified resistant to imazethapyr, but susceptible to chlorimuron, using a nondestructive leaf-disc assay. Sequencing of the ALS gene revealed that imazethapyr-resistant waterhemp plants from both populations had inferred amino acid substitutions at position 653 of ALS. Depending on the population, the serine at position 653 of ALS was substituted with either asparagine (S653N) or threonine (S653T). Waterhemp lines were derived from each population to create uniformly imidazolinone-resistant (IR) waterhemp biotypes, designated IR-62 and IR-101. ALS-inhibitor responses of each IR biotype were compared with a previously identified ALS inhibitor–resistant biotype with a tryptophan to leucine substitution at position 574 (W574L) and an herbicide-susceptible control. Whole-plant dose–response experiments with waterhemp biotypes containing W574L, S653N, or S653T mutations indicated that each biotype was resistant to imazethapyr, but only the biotype with a W574L mutation was resistant to thifensulfuron. In vitro ALS-activity assays revealed unique patterns of cross-resistance among protein extracts derived from each biotype in response to imazethapyr, thifensulfuron, cloransulam, and pyrithiobac. In conclusion, three different forms of target-site–based resistance to ALS inhibitors have been identified in waterhemp.

Cross-Resistance of Eclipta (Eclipta prostrata) in China to ALS Inhibitors Due to a Pro-197-Ser Point Mutation

Weed Science ◽  
2017 ◽  
Vol 65 (5) ◽  
pp. 547-556 ◽  
Author(s):  
Dan Li ◽  
Xiangju Li ◽  
Huilin Yu ◽  
Jingjing Wang ◽  
Hailan Cui
Keyword(s):  
Gene Sequence ◽  
Resistance Index ◽  
Acetolactate Synthase ◽  
Cross Resistance ◽  
Eclipta Prostrata ◽  
Whole Plant ◽  
Plant Assays ◽  
Als Inhibitors ◽  
Als Inhibitor

Eclipta, widespread in tropical, subtropical, and temperate regions, is one of the main malignant broadleaf weeds and thrives in moist and dryland fields. Field rates of acetolactate synthase (ALS) inhibitors have failed to control eclipta in some farmlands in China. One ALS inhibitor–resistant population (R) collected from Jiangsu province in China was confirmed in the greenhouse in our preliminary work. Whole-plant assays revealed that this R population was highly resistant to four sulfonylureas (pyrazosulfuron-ethyl, 134-fold; bensulfuron-methyl, 172-fold; metsulfuron-methyl, 30-fold; and tribenuron-methyl, 195-fold), two triazolopyrimidines (pyroxsulam, 98-fold; penoxsulam, 30-fold), and one pyrimidinylthio-benzoate (bispyribac-sodium, 166-fold) and was moderately resistant to two imidazolinones (imazethapyr, 10-fold; imazapic, 19-fold). ALS enzyme-activity assays showed insensitivity of the ALS from the R population (resistance index values ranged from 12 to 293) to all of the above ALS inhibitors in vitro. Chromatograms fromALSgene sequence analysis detected a homozygous Pro-197-Ser amino acid substitution in the R population. These results confirmed that the Pro-197-Ser substitution results in broad-spectrum cross-resistance to ALS inhibitors in the eclipta R population. To our knowledge, this study is the first to report broad cross-resistance to ALS inhibitors in eclipta and to obtain the full-lengthALSgene sequence.

In vitro and whole-plant magnitude and cross-resistance characterization of two imidazolinone-resistant sugarbeet (Beta vulgaris) somatic cell selections

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 24-29 ◽  
Author(s):  
Terry R. Wright ◽  
Donald Penner
Keyword(s):  
Somatic Cell ◽  
Shoot Culture ◽  
Acetolactate Synthase ◽  
Cross Resistance ◽  
Shoot Cultures ◽  
Als Inhibitors ◽  
Whole Plants ◽  
Inhibitor Resistance ◽  
Als Inhibitor

Acetolactate synthase (ALS)-inhibiting herbicide carryover in soil can severely affect sugarbeets grown in the year(s) following application. Two newly developed imidazolinone-resistant (IMI-R) sugarbeet somatic cell selections (Sir-13 and 93R30B) were examined for magnitude of resistance and extent of cross-resistance to other classes of ALS inhibitors and compared to a previously developed sulfonylurea-resistant (SU-R) selection, Sur. In vitro shoot culture tests indicated Sir-13 resistance was specific to imidazolinone (IMI) herbicides at approximately a 100-fold resistance compared to the sensitive control sugarbeet. Sur was 10,000-fold resistant to the sulfonylurea (SU) herbicide, chlorsulfuron, and 40-fold resistant to the triazolopyrimidine sulfonanilide (TP) herbicide, flumetsulam, but not cross-resistant to the IMI herbicides. 93R30B was selected for IMI-R from a plant homozygous for the SU-R allele,Sur, and displayed similar in vitro SU-R and TP-R as Sur, but also displayed a very high resistance to various IMI herbicides (400- to 3,600-fold). Compared to the sensitive control, Sir-13 was 300- and > 250-fold more resistant to imazethapyr and imazamox residues in soil, respectively. Response by whole plants to postemergence herbicide applications was similar to that observed in shoot cultures. Sir-13 exhibited > 100-fold resistance to imazethapyr as well as imazamox, and 93R30B showed > 250-fold resistance to both herbicides. 93R30B showed great enough resistance to imazamox to merit consideration of imazamox for use as a herbicide in these sugarbeets. Sir-13 showed a two- to threefold higher level of resistance in the homozygous vs. heterozygous state, indicating that like most ALS-inhibitor resistance traits, it was semidominantly inherited.

Multiple Pro197ALS Substitutions Endow Resistance to ALS Inhibitors within and among Mayweed Chamomile Populations

Weed Science ◽  
2011 ◽  
Vol 59 (3) ◽  
pp. 431-437 ◽  
Author(s):  
Suphannika Intanon ◽  
Alejandro Perez-Jones ◽  
Andrew G. Hulting ◽  
Carol A. Mallory-Smith
Keyword(s):  
Pacific Northwest ◽  
Genotypic Variation ◽  
Point Mutations ◽  
Acetolactate Synthase ◽  
Cross Resistance ◽  
Collection Site ◽  
Whole Plant ◽  
The Pacific ◽  
Als Inhibitors

Mayweed chamomile seeds were collected from six different fields across the Pacific Northwest. All populations (each collection site was considered a population) were suspected to have some level of acetolactate synthase (ALS) resistance. Greenhouse and laboratory studies were conducted to determine if these populations were resistant to three different classes of ALS inhibitors: sulfonylureas (SU), imidazolinones (IMI), and triazolopyrimidines (TP). A whole-plant dose–response andin vitroALS activity studies confirmed cross-resistance to thifensulfuron + tribenuron/chlorsulfuron (SU), imazethapyr (IMI), and cloransulam (TP); however, resistance varied by herbicide class and population. TwoALSisoforms of theALSgene (ALS1andALS2) were identified in mayweed chamomile; however, only mutations inALS1were responsible for resistance. No mutations were found inALS2. Sequence analysis of the partialALSgene identified four point mutations at position 197 (Pro197to Leu, Gln, Thr, or Ser) in the resistant populations. This study demonstrates genotypic variation associated with cross-resistance to ALS inhibitors within and between populations.

scholarly journals Nontarget-Site Resistance to ALS Inhibitors in Waterhemp (Amaranthus tuberculatus)

Weed Science ◽  
2015 ◽  
Vol 63 (2) ◽  
pp. 399-407 ◽  
Author(s):  
Jiaqi Guo ◽  
Chance W. Riggins ◽  
Nicholas E. Hausman ◽  
Aaron G. Hager ◽  
Dean E. Riechers ◽  
...  
Keyword(s):  
Acetolactate Synthase ◽  
Enzyme Assays ◽  
Whole Plant ◽  
Site Of Action ◽  
Amaranthus Tuberculatus ◽  
Resistance Trait ◽  
Als Inhibitors ◽  
Moderate Resistance ◽  
Inhibitor Resistance ◽  
Als Inhibitor

A waterhemp population (MCR) previously characterized as resistant to 4-hydroxyphenylpyruvate dioxygenase and photosystem II inhibitors demonstrated both moderate and high levels of resistance to acetolactate synthase (ALS) inhibitors. Plants from the MCR population exhibiting high resistance to ALS inhibitors contained the commonly found Trp574Leu ALS amino acid substitution, whereas plants with only moderate resistance did not have this substitution. A subpopulation (JG11) was derived from the MCR population in which the moderate-resistance trait was isolated from the Trp574Leu mutation. Results from DNA sequencing and ALS enzyme assays demonstrated that resistance to ALS inhibitors in the JG11 population was not due to an altered site of action. This nontarget-site ALS-inhibitor resistance was characterized with whole-plant dose–response experiments using herbicides from each of the five commercialized families of ALS-inhibiting herbicides. Resistance ratios ranging from 3 to 90 were obtained from the seven herbicides evaluated. Nontarget-site resistance to ALS has been rarely documented in eudicot weeds, and adds to the growing list of resistance traits evolved in waterhemp.

Target site–based penoxsulam resistance in barnyardgrass (Echinochloa crus-galli) from China

Weed Science ◽  
2019 ◽  
Vol 67 (3) ◽  
pp. 281-287 ◽  
Author(s):  
Jiapeng Fang ◽  
Tingting Liu ◽  
Yuhua Zhang ◽  
Jun Li ◽  
Liyao Dong
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Acetolactate Synthase ◽  
Target Site ◽  
Cross Resistance ◽  
Predicted Amino Acid Sequence ◽  
Sequence Analyses ◽  
Als Inhibitors ◽  
Higher Sensitivity

AbstractBarnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] is acknowledged to be the most troublesome weed in rice fields in Anhui and Jiangsu provinces of China. It cannot be effectively controlled using certain acetolactate synthase (ALS)-inhibiting herbicides, including penoxsulam. Echinochloa crus-galli samples with suspected resistance to penoxsulam were collected to identify the target site–based mechanism underlying this resistance. Populations AXXZ-2 and JNRG-2 showed 33- and 7.3-fold resistance to penoxsulam, respectively, compared with the susceptible JLGY-3 population. Cross-resistance to other ALS inhibitors was reported in AXXZ-2 but not in JNRG-2, and occasionally showed higher sensitivity than JLGY-3. In vitro ALS activity assays revealed that penoxsulam concentrations required to inhibit 50% of ALS activity were 11 and 5.2 times greater in AXXZ-2 and JNRG-2, respectively, than in JLGY-3. DNA and predicted amino acid sequence analyses of ALS revealed Ala-205-Val and Ala-122-Gly substitutions in AXXZ-2 and JNRG-2, respectively. Our results indicate that these substitutions in ALS are at least partially responsible for resistance to penoxsulam.

Resistance to Bensulfuron-Methyl in Water Plantain (Alisma plantago-aquatica) Populations from Chilean Paddy Fields

2008 ◽  
Vol 22 (4) ◽  
pp. 602-608 ◽  
Author(s):  
Rodrigo Figueroa ◽  
Marlene Gebauer ◽  
Albert Fischer ◽  
Marcelo Kogan
Keyword(s):  
Weed Management ◽  
Wide Spectrum ◽  
Acetolactate Synthase ◽  
Rice Fields ◽  
Integrated Weed Management ◽  
Cross Resistance ◽  
Content Type ◽  
Als Inhibitors

Bensulfuron-methyl (BSM) has been one of the most widely used herbicides in Chilean rice fields because it controls a wide spectrum of weeds and does not require field drainage for application. However, failures of BSM to control water plantain in rice fields have been noted since 2002. We assessed BSM effects on suspected resistant (CU1 and CU2) and susceptible (AN1) water plantain accessions collected in Chilean rice fields during 2004 and 2005. BSM rates resulting in 50% growth reduction (GR50) of CU2 and CU1 plants were 12- and 33-fold higher than for AN1 plants, respectively. Acetolactate synthase (ALS) activity assays in vitro suggested resistance in CU1 and CU2 was due to an ALS enzyme with reduced BSM sensitivity compared to the AN1 biotype. Resistance indices (RI), or ratios of the resistant to susceptibleI50values (BSM rate to inhibit ALS-enzyme activity by 50%), were 266 (CU2/AN1) and > 38,462 (CU1/AN1). This agreed with in vivo ALS activity assays whereRIwere 224 (CU2/AN1) and > 8,533 (CU1/AN1). Resistance levels detected in whole-plant or in vivo ALS activity assays were orders of magnitude lower than those detected in in vitro ALS activity studies suggesting nontarget site mechanisms may have mitigated BSM toxicity. However, a consistent ranking of BSM sensitivity levels (AN1 > CU2 > CU1) throughout all three types of assays suggests resistance is primarily endowed by low target site sensitivity. We conclude that susceptible and resistant water plantain biotypes coexist in Chilean paddies, and the use of integrated weed management involving herbicides with a different mode of action would be imperative to prevent further evolution of resistance to BSM and possibly cross-resistance to other ALS inhibitors. In vitro ALS-enzyme assays provided the best discrimination of resistance levels between biotypes.

scholarly journals Confirmation and Characterization of the First Case of Acetolactate Synthase (ALS)-Inhibitor—Resistant Wild Buckwheat (Polygonum convolvulus L.) in the United States

Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1496
Author(s):  
Balaji Aravindhan Pandian ◽  
Abigail Friesen ◽  
Martin Laforest ◽  
Dallas E. Peterson ◽  
P. V. Vara Prasad ◽  
...  
Keyword(s):  
Acetolactate Synthase ◽  
The United States ◽  
Cross Resistance ◽  
Wheat Field ◽  
Wild Buckwheat ◽  
Polygonum Convolvulus ◽  
First Case ◽  
Als Inhibitors ◽  
High Level ◽  
Als Inhibitor

Wild buckwheat (Polygonum convolvulus L.) is a problem weed and ALS-inhibitors (e.g., chlorsulfuron) are commonly used for its management. Recently, a population of wild buckwheat (KSW-R) uncontrolled with ALS-inhibitors was found in a wheat field in Kansas, USA. The objectives of this research were to determine the level and mechanism of resistance to chlorsulfuron and cross resistance to other ALS-inhibitors in the KSW-R population. In response to chlorsulfuron rates ranging from 0 to 16x (x = 18 g ai/ha), the KSW-R wild buckwheat was found >100-fold more resistant compared to a known ALS-inhibitor susceptible (KSW-S) wild buckwheat. Also, >90% of KSW-R plants survived field recommended rates of sulfonylurea but not imidazolinone family of ALS-inhibitors. A portion of the ALS gene covering all previously reported mutations known to bestow resistance to ALS-inhibitors was sequenced from both KSW-R and KSW-S plants. The Pro-197-Ser substitution that confers resistance to the sulfonylurea herbicides was found in KSW-R plants. Our results support the evolution of high level of chlorsulfuron resistance as a result of a mutation in the ALS-gene in KSW-R buckwheat. This is the first case of resistance to any herbicides in wild buckwheat in the US.

Multiple herbicide-resistant Palmer amaranth (Amaranthus palmeri) in Connecticut: confirmation and response to POST herbicides

2021 ◽  
pp. 1-7
Author(s):  
Jatinder S. Aulakh ◽  
Parminder S. Chahal ◽  
Vipan Kumar ◽  
Andrew J. Price ◽  
Karl Guillard
Keyword(s):  
Cropping Systems ◽  
Acetolactate Synthase ◽  
Palmer Amaranth ◽  
Effective Control ◽  
Herbicide Resistant ◽  
First Case ◽  
Whole Plant ◽  
Chlorimuron Ethyl ◽  
Als Inhibitors ◽  
Als Inhibitor

Abstract Palmer amaranth is the latest pigweed species documented in Connecticut; it was identified there in 2019. In a single-dose experiment, the Connecticut Palmer amaranth biotype survived the field-use rates of glyphosate (840 g ae ha−1) and imazaquin (137 g ai ha−1) herbicides applied separately. Additional experiments were conducted to (1) determine the level of resistance to glyphosate and acetolactate synthase (ALS) inhibitors in the Connecticut-resistant (CT-Res) biotype using whole-plant dose-response bioassays, and (2) evaluate the response of the CT-Res biotype to POST herbicides commonly used in Connecticut cropping systems. Based on the effective dose required for 90% control (ED90), the CT-Res biotype was 10-fold resistant to glyphosate when compared with the Kansas-susceptible (KS-Sus) biotype. Furthermore, the CT-Res biotype was highly resistant to ALS-inhibitor herbicides; only 18% control was achieved with 2,196 g ai ha−1 imazaquin. The CT-Res biotype was also cross-resistant to other ALS-inhibitor herbicides, including chlorimuron-ethyl (13.1 g ai ha−1), halosulfuron-methyl (70 g ai ha−1), and sulfometuron-methyl (392 g ai ha−1). The CT-Res Palmer amaranth was controlled 75% to 100% at 21 d after treatment (DAT) with POST applications of 2,4-D (386 g ae ha−1), carfentrazone-ethyl (34 g ai ha−1), clopyralid (280 g ae ha−1), dicamba (280 g ae ha−1), glufosinate (595 g ai ha−1), lactofen (220 g ai ha−1), oxyfluorfen (1,121g ai ha−1), and mesotrione (105 g ai ha−1) herbicides. Atrazine (2,240 g ai ha−1) controlled the CT-Res biotype only 52%, suggesting the biotype is resistant to this herbicide as well. Here we report the first case of Palmer amaranth from Connecticut with multiple resistance to glyphosate and ALS inhibitors. Growers should proactively use all available weed control tactics, including the use of effective PRE and alternative POST herbicides (tested in this study), for effective control of the CT-Res biotype.

Interactions between Sclerotinia sclerotiorum and other fungi on the phylloplane of lettuce

1987 ◽  
Vol 65 (8) ◽  
pp. 1633-1637 ◽  
Author(s):  
J. Mercier ◽  
R. D. Reeleder
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Close Contact ◽  
Trichoderma Viride ◽  
Leaf Disc ◽  
Whole Plant ◽  
Whole Plants ◽  
Protection Against Infection ◽  
Disc Assay

Selected fungi recovered from the phylloplane of lettuce were assayed, using in vitro and in vivo techniques, to determine their effectiveness as antagonists of ascospores of the lettuce drop pathogen, Sclerotinia sclerotiorum. On leaf discs, Trichoderma viride, Alternaria alternata, and Epicoccum purpurascens significantly reduced ascospore germ-tube elongation by 34.2, 60.6, and 38.3%, respectively. On whole plants, these three fungi significantly reduced infection by 40–93.3%. Isolates of Cladosporium cladosporioides and a red yeast inhibited ascospore elongation significantly in the in vitro leaf disc assay but failed to provide significant protection against infection by S. sclerotiorum in the in vivo whole-plant assay. Observations with the scanning electron microscope indicated that hyphae of T. viride and A. alternata came into close contact with ascospores on the leaf surface, suggesting parasitic relationships. Hyphae of E. purpurascens did not come into direct contact with ascospores and inhibition may have been due to production of antifungal compounds.

Corn (Zea mays) acetolactate synthase sensitivity to four classes of ALS-inhibiting herbicides

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 8-12 ◽  
Author(s):  
Terry R. Wright ◽  
Donald Penner
Keyword(s):  
Plant Protection ◽  
Enzyme Level ◽  
Acetolactate Synthase ◽  
Application Rate ◽  
Field Application ◽  
Cross Resistance ◽  
Commercial Development ◽  
Whole Plant ◽  
Imidazolinone Herbicides

In vitro acetolactate synthase (ALS) activity from three commercial imidazolinone-resistant corn hybrids (ICI 8692 IT, Pioneer 3751 IR, and Ciba 4393 IMR) was compared to imidazolinone-sensitive isogenic hybrid controls for sensitivity to 11 herbicides representing four classes of ALS-inhibiting herbicide chemistry. Acetolactate synthase activity from Pioneer IR and Ciba IMR was cross-resistant to all four classes of ALS inhibitors, ranging from 48- to 5,000-fold. The ICI IT hybrid displayed only four- to eightfold resistance to the six imidazolinone herbicides and the pyrimidinylthiobenzoate herbicide, pyrithiobac, but no cross-resistance to the sulfonylurea and triazolopyrimidine sulfonanilide herbicides. The four- to eightfold enzyme resistance to imidazolinone herbicides provides whole-plant resistance; however, the sevenfold enzyme resistance to pyrithiobac was insufficient to afford whole-plant protection to a field application rate of the herbicide. A second imidazolinone-specific resistance allele,XI-12, currently under commercial development, was examined for the level of dominance at the enzyme level. In the heterozygous state, imazethapyr resistance was fivefold, compared to 250-fold in the homozygous condition, indicatingXI-12is a semidominant trait. No cross-resistance to nicosulfuron or primisulfuron was observed in the heterozygousXI-12hybrid extracts nor to nicosulfuron in theXI-12homozygote; however, a fivefold resistance to primisulfuron was detected in theXI-12homozygote.

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